computerpad.java

该代码用JAVA实现了简单的数字计算功能

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import java.util.LinkedList;
import java.text.NumberFormat;

public class ComputerPad extends Frame implements ActionListener {
 
   NumberButton numberButton[];
   OperationButton operationButton[];
   Button 小数点按钮 ,正负号按钮, 退格按钮 ,求倒数按钮 ,等号按钮 ,清零按钮;
   Panel panel;
   JTextField resultShow;
  String  运算符号[] ={ "+","-","*", "/"};
  LinkedList 链表;
  boolean 是否按下等号= false;
  

  public ComputerPad() {
    super("计算器");
    链表= new LinkedList();

    numberButton = new  NumberButton[10];
    for(int i = 0; i<= 9; i++){
    numberButton[i] = new NumberButton(i);
    numberButton[i].addActionListener(this);
    }

   operationButton = new OperationButton[4];
  for(int i = 0; i<4; i++){
     operationButton[i] = new OperationButton(运算符号[i]);
     operationButton[i].addActionListener(this);
   }
  
   小数点按钮 = new Button("."); 
   正负号按钮 = new Button("+/-");
   退格按钮  = new Button("退格");
   求倒数按钮 = new Button("1/x");
    等号按钮 = new Button("=");
   清零按钮 = new Button("C");

  小数点按钮.setForeground(Color.red);
   正负号按钮.setForeground(Color.red);
   退格按钮.setForeground(Color.red); 
   求倒数按钮.setForeground(Color.blue); 
    等号按钮.setForeground(Color.blue); 
   清零按钮.setForeground(Color.blue);

  小数点按钮.addActionListener(this); 
   正负号按钮.addActionListener(this);
   退格按钮.addActionListener(this); 
   求倒数按钮.addActionListener(this); 
    等号按钮.addActionListener(this);  
   清零按钮.addActionListener(this); 

  resultShow = new JTextField(10);
  resultShow.setHorizontalAlignment(JTextField.RIGHT);
  resultShow.setEditable(false);
  resultShow.setForeground(Color.blue);
  resultShow.setFont( new Font("TimesRoman", Font.PLAIN, 14));
  resultShow.setBorder(new SoftBevelBorder(BevelBorder.LOWERED));
  resultShow.setBackground(Color.white);

 
  panel = new Panel();
  panel.setLayout(new GridLayout(4, 5));

  //面板中第1行
  panel.add(numberButton[1]);
  panel.add(numberButton[2]);
  panel.add(numberButton[3]);
  panel.add(operationButton[0]);
  panel.add(清零按钮);

 //面板中第2行
  panel.add(numberButton[4]);
  panel.add(numberButton[5]);
  panel.add(numberButton[6]);
  panel.add(operationButton[1]);
  panel.add(退格按钮);


 //面板中第3行
  panel.add(numberButton[7]);
  panel.add(numberButton[8]);
  panel.add(numberButton[9]);
  panel.add(operationButton[2]);
  panel.add(求倒数按钮);
 
 //面板中第4行
  panel.add(numberButton[0]);
  panel.add(正负号按钮);
  panel.add(小数点按钮);
  panel.add(operationButton[3]);
  panel.add(等号按钮);
  add(panel, BorderLayout.CENTER);
  add(resultShow, BorderLayout.NORTH);
  
  addWindowListener(new WindowAdapter()
          { public void windowClosing(WindowEvent e)
            { 
              System.exit(0);
            }
          });
 
 setVisible(true);
 setBounds(100,50,240,180);
 setResizable(true);
 validate();
 }

public void actionPerformed(ActionEvent e) {
  if(e.getSource() instanceof NumberButton)
 {
    NumberButton b = (NumberButton)e.getSource();

    if(链表.size() == 0 ){
    int number = b.getNumber();
    链表.add("" + number);
    resultShow.setText(" "+ number);
    是否按下等号 = false;
    }

    else if(链表.size() == 1 && 是否按下等号 == false){
      int number = b.getNumber();
      String num = (String)链表.getFirst();
      String s = num.concat(""+ number);
      链表.set(0, s);
      resultShow.setText(s);
    }

   else if(链表.size()== 1 && 是否按下等号 == true){
      int number = b.getNumber();
      链表.removeFirst();
      链表.add(" " +number);
      是否按下等号 = false;
      resultShow.setText(" "+ number);
     }
 
   else if(链表.size() == 2){
     int number = b.getNumber();
     链表.add( " "+number);
     resultShow.setText(" "+ number);
   }

   else if(链表.size() == 3){
    int number = b.getNumber();
    String num = (String)链表.getLast();
    String s = num.concat( ""+number);
    链表.set(2, s);
   resultShow.setText(s);
    }

  }
else if(e.getSource()  instanceof OperationButton){
   OperationButton b = (OperationButton)e.getSource();
   if(链表.size() == 1){
   String fuhao = b.getOperator();
   链表.add(fuhao);
    }
   else if(链表.size() == 2){
   String fuhao = b.getOperator();
   链表.set(1, fuhao);
    }
   else if(链表.size() == 3){
   String fuhao = b.getOperator();
   String number1 = (String)链表.getFirst();
   String number2 = (String) 链表.getLast();
   String 运算符号 = (String)链表.get(1);

   try{
    double n1 = Double.parseDouble(number1);
    double n2 = Double.parseDouble(number2);
    double n= 0;
   if(运算符号.equals("+"))
  { n = n1 + n2; }
   else if(运算符号.equals("-"))
  {n = n1 - n2; }
   else if(运算符号.equals("*"))
  {n = n1 * n2; }
   else if(运算符号.equals("/"))
  {n = n1 / n2; }
   链表.clear();
   链表.add( " " +n);
   链表.add(fuhao);
   resultShow.setText(" "+ n);
   }
  catch(Exception ee){}
   }
 }

else if(e.getSource() == 等号按钮) {
  是否按下等号 = true;

  if(链表.size( ) == 1 || 链表.size() == 2){
  String num = (String)链表.getFirst();
  resultShow.setText(" "+ num );
  }

  else if(链表.size() == 3){
   String number1 = (String)链表.getFirst();
   String number2 = (String)链表.getLast();
   String 运算符号 = (String)链表.get(1);
   try{
    double n1= Double.parseDouble(number1);
    double n2 = Double.parseDouble(number2);
    double n = 0;
    if(运算符号.equals("+"))
  { n = n1 + n2; }
   else if(运算符号.equals("-"))
  {n = n1 - n2; }
   else if(运算符号.equals("*"))
  {n = n1 * n2; }
   else if(运算符号.equals("/"))
  {n = n1 / n2; }
  resultShow.setText( " "+ n);
  链表.set(0," "+ n);
  链表.removeLast();
  链表.removeLast();
 }
 catch (Exception ee){}
 }
}

else if(e.getSource() == 小数点按钮) {
  if(链表.size() == 0)
  { 是否按下等号 = false; }
  else if(链表.size() ==1){
  String dot = 小数点按钮.getLabel();
  String num = (String)链表.getFirst();
  String s = null;
  if(num.indexOf (dot) == -1)
  {
    s = num.concat(dot);
    链表.set(0,s);
   }
 else {
    s = num;
   }
  链表.set(0, s);
  resultShow.setText(s);
 }
 
 else if(链表.size() == 3 ){
   String dot = 小数点按钮.getLabel();
   String num = (String)链表.getLast();
   String s = null;
   if(num.indexOf(dot) == -1 ){
      s =  num.concat(dot);
      链表.set(2,s);
    }
   else {
     s  = num ;
      }
   resultShow.setText(s);
     }
  }

  else if(e.getSource() == 退格按钮){
   if(链表.size() == 1){
      String num = (String)链表.getFirst();
      if(num.length() >= 1){
        num = num.substring(0, num.length() - 1);
       链表.set(0,num);
       resultShow.setText(num);
       }
   else {
      链表.removeLast();
      resultShow.setText("0");
      }
   }
  else if(链表.size()== 3){
    String num = (String)链表.getLast();
    if(num.length() >= 1){
     num = num.substring(0, num.length() -1);
     链表.set(2, num);
     resultShow.setText(num);
     }
    else {
      链表.removeLast();
      resultShow.setText("0");
      }
     }
  }

 else if(e.getSource() == 正负号按钮){
     if(链表.size() == 1){
        String number1 = (String)链表.getFirst();
        try{
         double d = Double.parseDouble(number1);
         d = -1* d;
        String str = String.valueOf(d);
        链表.set(0, str);
         resultShow.setText(str);
       }
      catch(Exception ee){ }
    }

  else if(链表.size() == 3){
    String number2 = (String)链表.getLast();
    try{
      double d = Double.parseDouble(number2);
      d = -1/d;
      String  str= String.valueOf(d);
      链表.set(2, str);
      resultShow.setText(str);
      }
     catch(Exception ee){}
     }
     }

 else if(e.getSource() == 求倒数按钮){
      if(链表.size() == 1 || 链表.size() == 2){
       String number1 = (String)链表.getFirst();
      try{
       double d = Double.parseDouble(number1);
       d = 1.0/d;
       String str= String.valueOf(d);
       链表.set(0, str);
       resultShow.setText(str);
       }
      catch(Exception ee){}
     }
     else if ( 链表.size() ==    3){
            String number2 = (String)链表.getLast();
        try{
           double d = Double.parseDouble(number2);
           d = 1.0/d;
           String str = String.valueOf(d);
           链表.set(0, str); 
           resultShow.setText(str);
          } catch (Exception ee){}
    }
   }

else if(e.getSource() == 清零按钮)
  {
    是否按下等号 = false;
    resultShow.setText(" 0");
    链表.clear();
   }
  }

public static void main(String args[]){
    new ComputerPad();
   }
}